A constant problem with cycling after dark is the need for bright, reliable and theft-proof (or dirt cheap) lights.
For years now, I’ve favoured using old-style bolt-on battery lights together with dynamo lights. This gives redundancy and usually adequate light. And as both are bolted firmly to the bike, I’ve never had a problem with theft. However, more recently, I have wanted brighter lights. The reasons for this are
- to be more visible
- to be able to see well off the road
- to help me detect black-clothed unlit ‘stealth’ cyclists in winter on my commute across Midsummer Common.
I decided to use a 12-volt system. The obvious lights were the sealed 12 V halogen spot lamps designed for home use, so long as they could be attached to my cycle in a robust manner and did not fail prematurely due to vibration. It turned out that it was possible to construct an entire lighting system for a little less than £10, which made it worth trying.
You will need soldering skills to construct such a light yourself, and I take no responsibility for burnt fingers, burnt bicycles, exploded batteries, etc. Don’t take these as full instructions. The critical parts include:
- A battery. A 12 V 2.1 Ah (ampere hour) battery weighs about 800 g, and this is what I usually use. It gives less than one hour’s lighting, but this is more than enough for my commute. You could use a heavier, higher capacity battery, or a NiCd or other battery if you prefer, so long as it is 12 V, but I recommend avoiding disposable batteries (20-watt lighting would be expensive with these). I bought mine from Greenweld Electronics, a mail-order surplus supplier. They are also sometimes available from Bull Electrical, a similar surplus company, or locally, from Gee’s in Mill Road.
- The mechanical structure consists of two Jubilee clips and some 40 mm plumbing parts, which are a perfect fit for the lamp. These I bought locally from Ridgeon’s.
- A fuse – very important. A shorted battery could easily cause a fire.
- A Philips Standard Line Halogen Bulb, 12 V 20 W 10° (type no. 6642, aANSI no. ESX). Must have front glass. I have one light with a 36° bulb (more common); this works fine, but I am wary of dazzling oncoming traffic. I recommend pointing the bulb slightly downwards. You get a longer-range light with the 10° bulb, but the wider one may be more suitable off the road.
- A charger. To correctly charge a sealed lead-acid battery, you need a voltage-regulated supply. Suitable ready-made chargers cost £20 upwards. Don’t use a car battery (or any other unregulated) charger, because this may ruin your battery. Other types of battery need their own special chargers.
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My lights have been in use for six months now and the bulb has not failed yet. I have found that when I am riding fast with the bright light, cars seem less likely to emerge from side streets in front of me, possibly because they are not sure whether I am a cyclist or a motor-cyclist.
Of course, this light is not built to the British Standard, which specifies a tiny bulb powered by small batteries. I find it difficult to believe that a case could be brought that I was inadequately lit with my light. However, I am still an advocate of redundancy in lighting: it would probably be a good idea to have, say, a dynamo set in case the battery runs out, and to make sure your bike conforms to the letter of the law.
David Hembrow